Inset-type fastener elements are useful for connecting various types of structures to other structures or objects. This type of fastener element is generally anchored into the structure and has an engagement portion to which a screw fastener or the like is secured in order to connect an object to the structure. This arrangement is particularly advantageous when a strong connection between the structure and the object cannot readily be obtained by securing the fastener directly to the structure without an intervening fastener element.
Sandwich panels of the type used extensively in the aircraft industry are one type of structure which is commonly connected to other structures or objects by use of inset fastener elements. In order to provide a secure anchor in the cellular honeycomb core of the panel, the inset fastener is molded into a cavity formed in the core by use of a potting material. A problem that has arisen in connection with such molded-in installations is that it is difficult to precisely align the fastener element with the fastener receiving hole or other engagement means in the object or structure to be connected to the panel.
The applicant's U.S. Pat. No. 4,812,193, granted Mar. 14, 1989, discloses improvements in molded-in type inset fastener elements which are specifically directed toward providing a stronger connection between the fastener element and the sandwich panel The disclosed fastener element has a stem with flow control disks and diametrically opposite flat chord surfaces to control flow of potting material introduced into a cavity in which the stem has been positioned. The fastener element, including the stem, is a single integral member with a center axial opening for engaging a screw. Therefore, once the potting material has set to install the element, the position of the threads cannot be adjusted to correct for misalignments.
U.S. Pat. No. 3,646,981, granted Mar. 7, 1972, to G. Barnes, discloses an insert for a sandwich panel which includes an inner internally threaded tubular member and an outer ribbed sleeve The tubular member and sleeve are joined together so that there will be no relative motion therebetween and are independently anchored in a cavity in the panel. Therefore, once the insert is installed in the panel, the position of the internal threads on the tubular member cannot be adjusted to correct for misalignments.
U.S. Pat. No. 3,695,324, granted Oct. 3, 1972, to B. Gulistan, discloses a floating nut device having a nut portion with opposite outwardly projecting tabs that are received into opposite side openings in a receptacle portion. The receptacle portion has an opening extending therethrough and bears against an outer surface of the workpiece. An attaching sleeve also has opposite tabs that are received into the side openings in the receptacle portion. The sleeve has a tubular section that extends through a central opening in the workpiece and is secured thereto by bending its outer end against the opposite surface of the workpiece. The receptacle portion provides clearance to allow floating movement of the nut to allow a bolt which is misaligned with the opening in the workpiece to be engaged in the nut. In two alternative embodiments, the receptacle portion and the attaching sleeve are formed by a single receptacle member.
The above patents and the prior art discussed and/or cited therein should be carefully considered for the purpose of putting the present invention into proper perspective relative to the prior art.